X-ray imaging system and method with a real-time controllable 3D X-ray attenuator

ABSTRACT

An X-ray imaging system including an X-ray source, an X-ray collimator, a real-time controllable 3D X-ray attenuator, a digital X-ray detector, and a system controller coupled to the X-ray radiation source, the collimator, the real-time controllable 3D X-ray attenuator, and the digital X-ray detector for controlling the real-time controllable 3D X-ray attenuator to reduce X-ray radiation dose and improve image quality. The real-time controllable 3D X-ray attenuator includes a top panel, a bottom panel, at least one sidewall joining the top panel to the bottom panel, an open area between the top panel, bottom panel, and at least one 2D pixel array coupled to at least one of the top panel and the bottom panel, the at least one 2D pixel array having a plurality of pixels of thin film electric coils and switching thin film field-effect transistors, wherein the open area is at least partially filled with a mixture of ferromagnetic material and medium X-ray attenuation material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/098,821, filed on Dec. 31, 2014, the entirety ofwhich is incorporated herein by reference.

BACKGROUND

This disclosure relates generally to X-ray imaging systems and methods,and more particularly to X-ray imaging system and method with areal-time controllable three-dimensional (3D) X-ray attenuator thatfilters an X-ray beam and generates an X-ray beam with a variableradiation dose according to a two-dimensional (2D) X-ray image intensitymap.

Better image quality and the lower X-ray radiation dose to a patient orsubject being imaged are always the top requirement on any X-ray imagingsystem and method. However, these two requirements contradict eachother. Generally, for a given X-ray imaging system and method, higherimage quality requires higher X-ray radiation dose and lower X-rayradiation dose yields lower image quality.

Existing X-ray imaging systems and methods determine X-ray techniquesbased on either the contrast-to-noise ratio (CNR) or the signal-to-noiseratio (SNR) of the densest or thickest portion of a patient's anatomy orsubject being imaged, which means that the X-ray radiation dose in allother regions of the anatomy is unnecessarily higher than it requires,which not only results in unnecessarily higher X-ray radiation dose tothe patient, but lower image contrast as well.

The present disclosure allows programming a lower X-ray radiation doseto areas of patent anatomy having a lower density, such as tissue orinternal organs, and programming a higher X-ray radiation dose to areasof patient anatomy having a higher density, such as bone. This resultsin patient anatomy receiving only the necessary X-ray radiation dose,resulting in an overall lower radiation dose.

The present discloser discloses a real-time controllable 3D X-rayattenuator that forms an X-ray beam that reduces X-ray radiation dose tothe patient or subject being imaged, improves image quality by extendingthe dynamic range of the X-ray imaging system, and eliminates imageburnout. With proper system and method control mechanisms, thisdisclosure can reduce X-ray radiation dose to the patient, enhance imagequality, and improve X-ray imaging system and method reliability.

BRIEF DESCRIPTION

In accordance with an aspect of the present disclosure, an X-ray imagingsystem comprising an X-ray source that emits X-ray radiation; an X-raycollimator positioned adjacent to the X-ray source; a real-timecontrollable 3D X-ray attenuator; a digital X-ray detector; and a systemcontroller coupled to the X-ray source, the X-ray collimator, thereal-time controllable 3D X-ray attenuator, and the digital X-raydetector for controlling the real-time controllable 3D X-ray attenuatorto reduce X-ray radiation dose and improve image quality.

In accordance with an aspect of the present disclosure, a real-timecontrollable 3D X-ray attenuator comprising a top panel; a bottom panel;at least one sidewall joining the top panel to the bottom panel; an openarea between the top panel, bottom panel, and at least one sidewall; andat least one 2D pixel array coupled to at least one of the top panel andthe bottom panel, the at least one 2D pixel array having a plurality ofpixels of thin film electric coils and switching thin film field-effecttransistors; wherein the open area is at least partially filled with amixture of ferromagnetic material and medium X-ray attenuation material.

In accordance with an aspect of the present disclosure, a method ofcontrolling a 3D X-ray attenuator in real-time, the method comprisingthe steps of acquiring a pre-acquisition image or an image frame from anX-ray imaging system; dividing the pre-acquisition image or image frameinto N×N regions through the use of an image processing system;determining the average X-ray image intensity in each N×N region tocreate a 2D X-ray image intensity map; determining the desired X-rayattenuation in each N×N region from the average X-ray image intensity ineach N×N region; and using the desired X-ray attenuation in each N×Nregion of the 2D X-ray image intensity map to control current applied toeach coil of the 3D X-ray attenuator.

Various other features, aspects, and advantages will be made apparent tothose skilled in the art from the accompanying drawings and detaileddescription thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary embodiment of an X-ray imagingsystem;

FIG. 2 is a schematic diagram of an exemplary embodiment of a real-timecontrollable 3D X-ray attenuator;

FIG. 3 is a schematic diagram of an exemplary embodiment of a 2D pixelarray of the real-time controllable 3D X-ray attenuator of FIG. 2;

FIG. 4 is a schematic diagram of an exemplary embodiment of a datamodule of the 2D pixel array of FIG. 3;

FIG. 5 is a schematic diagram of an exemplary embodiment of a scanmodule of the 2D pixel array of FIG. 3;

FIG. 6 is an exemplary flow diagram of an embodiment of a method forcontrolling a 3D X-ray attenuator in real-time;

FIG. 7 is an image diagram of an exemplary embodiment of a 2D X-rayimage intensity map;

FIG. 8 is a schematic diagram of an exemplary embodiment of a 2D pixelarray of a real-time controllable 3D X-ray attenuator; and

FIG. 9 is a schematic diagram of an exemplary embodiment of a real-timecontrollable 3D X-ray attenuator.

DETAILED DESCRIPTION

Referring generally to FIG. 1, an X-ray imaging system is representedand referenced generally by reference numeral 10. In the illustratedembodiment, the X-ray imaging system 10, as adapted, is a digital X-rayimaging system. The X-ray imaging system 10 is designed both to acquireimage data and to process the image data for display in accordance withthe present technique. Throughout the following discussion, however,while basic and background information is provided on the digital X-rayimaging system used in medical diagnostic applications, it should beborn in mind that aspects of the present techniques may be applied toX-ray imaging systems, used in different settings (e.g., projectionX-ray imaging, computed tomography imaging, tomosynthesis imaging,fluoroscopic imaging, mammographic imaging, radiographic imaging, etc.)and for different purposes (e.g., parcel, baggage, vehicle and componentinspection, etc.).

FIG. 1 illustrates a block diagram of an exemplary embodiment of anX-ray imaging system 10. The X-ray imaging system 10 includes an X-raysource 12 that emits X-ray radiation 14 and is positioned adjacent to anX-ray collimator 15 and a real-time controllable 3D X-ray attenuator 16.The X-ray attenuator 16 filters a beam of X-ray radiation 17 coming fromthe X-ray collimator 15 into a filtered beam of X-ray radiation 18 thatis delivered onto a region in of a subject 20, such as a human patient,an animal or an object, is positioned. A portion of the X-ray radiation22 passes through the subject 20 and impacts a digital X-ray detector24. The digital X-ray detector 24 converts X-ray photons received on thesurface of an X-ray detector panel array (not shown) to lower energyphotons, and subsequently to electric signals which are acquired andprocessed by an image processing system 26 to reconstruct an image ofthe subject features or anatomy on an image display 28. The filteredbeam of X-ray radiation 18 is uniformly radiated on a field of view ofthe subject 20 or patient anatomy being imaged. The probability of afiltered X-ray radiation 18 being absorbed by the subject 20 or patientanatomy depends on two things. One is the energy of the filtered X-rayradiation 18 and the other is the property of the matter in the path ofthe filtered X-ray radiation 18 including the thickness, density, andtype of matter of the patient's anatomy. Thus, the X-ray beam 22 aftertraveling through the subject 20 reflects the thickness and the type ofmatter inside the subject 20 or patient anatomy. An X-ray beam with avariable 2D X-ray radiation intensity is achieved by introducing the 3DX-ray attenuator 16 between the X-ray collimator 15 and the subject 20.

In the embodiment illustrated in FIG. 1, the X-ray imaging system 10 maybe a stationary X-ray imaging system disposed in a fixed X-ray imagingroom. It will be appreciated, however, that the presently disclosedtechniques may also be employed with other X-ray imaging systems,including a mobile X-ray imaging system in other embodiments.

Imagine that if all the X-ray photons in the filtered X-ray radiationbeam 18 are absorbed by the subject 20 or patient anatomy, we would havea flat image without any anatomical information because all the pixelsin the image would have exactly the same value. On the other hand, ifall the X-ray photons in the filtered X-ray radiation beam 18 penetratethrough the subject 20 or patient without being absorbed, we would nothave any anatomical information for the same reason.

The X-ray source 12, the collimator 15, the real-time controllable 3DX-ray attenuator 16, digital X-ray detector 24, image processing system26, and image display 28 may be coupled to the system controller 30. Thesystem controller 30 may include a power supply, collimator controller,detector controller and at least one processor and memory. The at leastone processor, memory, detector controller, collimator controller,source controller, and all of the electronics and circuitry within thesecomponents may receive power from the power supply. The memory may storevarious configuration parameters, calibration files, and detectoridentification data. In addition, the memory may store patientinformation to be combined with the image data to generate a DICOMcompliant data file. In an exemplary embodiment, the X-ray source 12 maybe coupled to an X-ray source controller, which may be part of thesystem controller 30 configured to command X-ray emission of X-rays forimage exposures. In an exemplary embodiment, the power supply mayinclude one or more batteries.

The system controller 30, memory, and processor may be coupled to anoperator workstation 32, image storage system 34, and image in/outinterface 36. The system controller 30 may be in communication with theoperator workstation 32, image storage system 34, and image in/outinterface 36 over a network via the wired or wireless connection. Thesystem controller 30 may be configured to wirelessly transmit ortransmit through a wired connection partially processed or fullyprocessed X-ray image data to the image storage system 34. The imagestorage system 34 may include a picture archiving and communicationsystem (PACS), a radiology information system (RIS), and/or a hospitalinformation system (HIS). The image storage system 34 may store sampleddata gathered during the imaging mode as well as X-ray image data.

FIG. 2 illustrates a schematic diagram of an exemplary embodiment of areal-time controllable 3D X-ray attenuator 16. The real-timecontrollable 3D X-ray attenuator 16 includes a top panel 42, a bottompanel 44, at least one sidewall 46 joining the top panel 42 to thebottom panel 44, and an open area 48 between the top panel 42, bottompanel 44, and at least one sidewall 46. The top panel 42 and the bottompanel 44 are spaced apart from each other by the at least one sidewall46 and are parallel with each other. In an exemplary embodiment, the toppanel 42, bottom panel 44, and at least one sidewall 46 may be made of alow X-ray attenuation material such as glass, carbon fiber, aluminum,etc. The open area 48 is at least partially filled with a mixture offerromagnetic material and medium X-ray attenuation material (notshown). The mixture of ferromagnetic material and medium X-rayattenuation material acts as a filter that only allows a portion of thebeam of X-ray radiation 17 to go through the 3D X-ray attenuator 16. The3D X-ray attenuator 16 reduces X-ray radiation dose to the patient 20.The total X-ray attenuation of the mixture of ferromagnetic material andmedium X-ray attenuation material depends on the X-ray attenuation ofeach material as well as the percentage of each material used.

The mixture of ferromagnetic material and medium X-ray attenuationmaterial may be in the form of solid material or liquid material. In anexemplary embodiment, the mixture may include a plurality of tinymetallic balls made of a ferromagnetic material such as iron (Fe) mixedwith another medium X-ray attenuation material such as copper (Cu). Inanother exemplary embodiment, a small percentage of other materials maybe mixed with these materials. For example, the iron (Fe) may be mixedwith a small percentage of neodymium (Nd) and the copper (Cu) may bemixed with a small percentage of tungsten (W) to reduce the amount ofmaterial needed inside of the 3D X-ray attenuator 16. In a preferredembodiment, the percentage of the medium X-ray attenuation materials (Feand Cu) is much larger than the percentage of the high attenuationmaterials (Nd and W). In a preferred embodiment, the diameter of thetiny metallic balls shall be as small as possible, typically, in therange of micrometers to tens of micrometers.

In another exemplary embodiment, the mixture of ferromagnetic materialand medium X-ray attenuation material may be in the form of a liquid(ferrofluid). A ferrofluid is a liquid that becomes strongly magnetizedin the presence of a magnetic field. In a preferred embodiment, theferrofluid may be made from nanostructured particles of ferromagneticand medium X-ray attenuation materials such as iron (Fe) and/or copper(Cu) suspended in a carrier fluid such as water. In another exemplaryembodiment, the ferrofluid may also include a small percentage ofneodymium (Nd) and/or tungsten (W) to reduce the amount of materialneeded inside the 3D X-ray attenuator 16. In a preferred embodiment, thepercentage of the medium X-ray attenuation materials (Fe and Cu) is muchlarger than the percentage of the high attenuation materials (Nd and W).

The real-time controllable 3D X-ray attenuator 16 further includes atleast one two-dimensional (2D) pixel array 50 with a plurality of pixels52 of thin film electric coils 54 and switching thin film field-effecttransistors 56 as shown in FIG. 3. Each pixel 52 of the pixel array 50includes a thin film electric coil 54 connected to a data line 58 and ascan line 60 through the thin film field-effect transistor 56. In anexemplary embodiment, the 2D pixel array 50 may be integrated into orattached to an inner or outer surface of the top panel 42. In anexemplary embodiment, the 2D pixel array 50 may be integrated into orattached to an inner or outer surface of the bottom panel 44. In anotherexemplary embodiment, the 2D pixel array 50 may be integrated into orattached to an inner or outer surface of both the top 42 and bottom 44panels of the real-time controllable 3D X-ray attenuator 16.

As mentioned above, FIG. 3 illustrates a schematic diagram of anexemplary embodiment of the 2D pixel array 50 of the real-timecontrollable 3D X-ray attenuator 16 of FIG. 2. The 2D pixel array 50includes a plurality of pixels 52 with thin film electric coils 54 andswitching thin film field-effect transistors 56. Each pixel 52 includesa thin film electric coil 54 connected to a thin film field effecttransistor 56 functioning as a switch and located at the intersection ofa data line 58 and a scan line 60. The data lines 58 are coupled to adata module 62 and the scan lines 60 are coupled to a scan module 64.The data module 62 and scan module 64 are configured to control thepixels 52 of the pixel array and to control the real-time controllable3D X-ray attenuator 16.

The pixels 52 of the pixel array 50 are organized into a plurality ofrows and columns. The gates of the thin film field-effect transistors 56in each row are connected together and coupled to a scan line 60.Similarly, the sources of the thin film field-effect transistors 56 ineach column are connected together and coupled to a data line 58. Thedrains of the thin film field-effect transistors 56 are connected to thethin film electric coils 54. The real-time controllable 3D X-rayattenuator 16 and related components and circuitry of the 2D pixel array50 receives power from the system controller 30 and related powersupplies.

The present disclosure provides the ability of the real-timecontrollable 3D X-ray attenuator 16 to independently turn on and offeach pixel 52 in the pixel array 50. The arbitrarily desirable shape ofthe filtered X-ray beam 18 is formed through magnetic fields generatedby applying current to the coils 54 of the 2D pixel array 50 therebycontrolling the location of the mixture of ferromagnetic material andmedium X-ray attenuation material under the individual pixels 54 withinthe open area of the real-time controllable 3D X-ray attenuator 16. Theapplication of electric current in the electric coils 54 creates amagnetic field that attracts the mixture of ferromagnetic material andmedium X-ray attenuation material inside the real-time controllable 3DX-ray attenuator 16 to the coils 54 that have current running throughthem, thereby attenuating X-ray beam radiation in areas where a mixtureof ferromagnetic material and medium X-ray attenuation material islocated under the coils 54 that have current running through them. TheX-ray beam radiation attenuation is determined by the thickness of themixture of ferromagnetic material and medium X-ray attenuation materialunder each of the pixel coils 54.

In an exemplary embodiment, the disclosed pixel array 50 as well as thedata module 62 and scan module 64 electronics are manufactured by, forexample, amorphous silicon or CMOS technologies that are used to producepixel arrays of digital X-ray detector panels. The thin film electriccoils 54 may be made of electrically conductive materials such asaluminum or copper.

Please note that the pixel size of the 3D X-ray attenuator 16 does nothave to be aligned with the pixel size of the digital X-ray detector 24.Typically, the number of pixels in a 3D X-ray attenuator is less thanthat of a digital X-ray detector. That is because the pixel size of adigital X-ray detector has to be small enough to achieve desired spatialresolution, while the 3D X-ray attenuator only needs to distinguishregions of anatomy with significantly different densities andthicknesses.

FIG. 4 illustrates a schematic diagram of an exemplary embodiment of adata module 62 of the 2D pixel array 50 of FIG. 3. In an exemplaryembodiment, the data module 62 may have a plurality of channels 69. Eachchannel 69 preferably includes a digital to analog (D/A) convertor 70connected to a data line 58. Each of the plurality of channels 69 in thedata module 62 are preferably connected to a data bus 66 through amultiplexer 68 such that each channel 69 and data line 58 may provide adifferent amount of electric current to each coil 54 of the pixel array50 at the same time.

FIG. 5 illustrates a schematic diagram of an exemplary embodiment of ascan module 64 of the 2D pixel array 50 of FIG. 3. In an exemplaryembodiment, the scan module 64 provides the scan lines 60 with either apositive voltage (V_(on)) to turn on a field-effect transistor 56, sothat the electric coil 54 coupled to the field-effect transistor of apixel 52 is connected to a corresponding data line 58 or a negativevoltage (V_(off)) to turn off a field-effect transistor 56, so that theelectric coil 54 coupled to the field-effect transistor of a pixel 52 isdisconnected from a corresponding data line 58.

In the particular example shown in FIG. 5, all outputs 72 (scan lines60) of the scan module 64 are at a negative voltage (V_(off)) exceptthat the second output 73 (scan line 60) of the scan module 64 is at apositive voltage (V_(on)). In this case, only the pixels 52 in thesecond row of the pixel array 50 are connecting to the data lines 58.The pixels 52 in all other rows of the pixel array 50 are disconnectedfrom data lines 58.

Even though all of the pixels 52 in a column of the pixel array 50 usethe same data line 58, the scan module 64 selects one row of pixels 52at a time to be connected to a data line 58. By feeding the digital toanalog (D/A) converter 70 of a particular data module channel 69 withthe desirable digits during the period of the time when the row ofpixels 52 is selected, we can flow a different amount of electriccurrent to the pixel array 50.

Since all pixels 52 have the same electric coil 54, the higher theelectric current flowing through the electric coil, the stronger themagnetic field it produces and the more the mixture of ferromagneticmaterial and medium X-ray attenuation material inside the real-timecontrollable 3D X-ray attenuator 16 is attracted to the magnetic fieldof the coils 54 of the pixels 52. Therefore, the amount of mixture offerromagnetic material and medium X-ray attenuation material and amountof X-ray attenuation is controlled by the amount of current applied toeach coil 54 in the 2D pixel array 50.

Please note that the electric current flowing into the pixel array 50row by row and the magnetic field of a pixel 52 is in an on-off-on-offpattern. As long as the magnetic field of the pixels 52 is re-freshedfast enough, the mixture of ferromagnetic material and medium X-rayattenuation material is in an equilibrium condition, keeping thefiltered X-ray beam 18 from changing for a given 2D X-ray imageintensity map.

FIG. 6 illustrates an exemplary flow diagram of an embodiment of amethod 600 for controlling a 3D X-ray attenuator in real-time. Themethod 600 begins at step 602 by acquiring a pre-acquisition image in asingle-shot X-ray application, such as in a radiography imageacquisition, or an image frame at the beginning of a fluoroscopic imagesequence from an X-ray imaging system. The next step 604 includes havingan image processing system divide the pre-acquisition image or the imageframe into a plurality of N×N regions. At step 606, the image processingsystem is used to determine the average X-ray image intensity in each ofthe N×N regions generating a 2D X-ray image intensity map. The 2D X-rayimage intensity map is generated based on either the low dosepre-acquisition image in a single shot type of X-ray application, suchas radiography imaging or an image frame at the beginning of afluoroscopic imaging sequence. The 2D X-ray image intensity map is basedon the X-ray image intensity with black meaning low X-ray imageintensity and white meaning high X-ray image intensity. In other words,bone is depicted as black in the X-ray image and tissue and organs aredepicted as white in the X-ray image. Image intensity is linearlyproportional to the X-ray intensity. In other words, if you double theX-ray intensity you will double the X-ray image intensity. In step 608,an X-ray imaging system controller is used to determine the desiredX-ray attenuation in each of the N×N regions from the average X-rayimage intensity determined in the 2D X-ray image intensity map. Thelower X-ray image intensity in each N×N region, depicted by whiteregions, the more X-ray attenuation is required. Similarly, the higherX-ray image intensity in each N×N region, depicted by black regions, theless X-ray attenuation is required. The final step of the method, step610, includes using the desired X-ray attenuation in each N×N region ofthe 2D X-ray image intensity map to control the current applied to eachpixel or coil of the 3D X-ray attenuator by the X-ray imaging systemcontroller to control X-ray attenuation to different areas of apatient's anatomy. It is important to be able to control the X-ray doseprovided to different areas of anatomy of a patient undergoing an X-rayimaging acquisition or sequence. For example, it is desirable to providea lower X-ray dose around thinner or less dense anatomy, like tissue ororgans. The X-ray imaging system generates an X-ray beam with a variableX-ray radiation intensity or dose according to a 2D X-ray imageintensity map.

FIG. 7 illustrates an image diagram of an exemplary embodiment of a 2DX-ray image intensity map 700. The 2D X-ray image intensity map 700 isgenerated based on either a low dose pre-acquisition image in a singleshot type of X-ray application, such as radiography imaging or an imageframe at the beginning of a fluoroscopic imaging sequence. The image 700shown in FIG. 7 is an example of a low dose pre-acquisition image or animage frame from a fluoroscopic imaging sequence. The image is dividedinto a matrix of N×N regions. In the example shown in FIG. 7, the imageis divided into a matrix of 8×8 regions 706 by horizontal lines 702 andvertical lines 704. The lighter or whiter the image in each of theregions 706, the more X-ray attenuation is required. Similarly, thedarker or blacker the image in each region 706, the less X-rayattenuation is required.

The 2D X-ray image intensity map 700 includes darker or blacker areas710 having a low X-ray image intensity that require lower X-rayattenuation and thus a higher X-ray radiation dose, and lighter orwhiter areas 708 having a high X-ray image intensity that require higherX-ray attenuation and thus a lower X-ray radiation dose. X-ray imageintensity is linearly proportional to the X-ray intensity.

The X-ray intensity map 700 is proportional to the X-ray attenuation ofthe patient anatomy through, for instance, feedback of the digital X-raydetector in an image frame for multiple frame type of imagingapplications such as fluoroscopic imaging or a low dose pre-acquisitionimage for a single exposure type of application such as in radiographicimaging, to achieve the maximum in X-ray radiation dose reductions. Aresultant X-ray image is combined with an X-ray intensity map to producea final image. A benefit of the disclosed technology is to extend thedynamic range of the X-ray imaging system and eliminate image burnout.

The 2D X-ray image intensity map 700 is based on the X-ray imageintensity with black meaning low X-ray image intensity and white meaninghigh X-ray image intensity. In a surgical application, bone appears asblack in the X-ray image, while soft tissue appears as white in theX-ray image. This is the direct opposite in other X-ray imagingmodalities, such as radiology and mammography. In these modalities, theX-ray image intensity is inverted, meaning bone appears as white in theX-ray image, while soft tissue appears as black in the X-ray image.

X-ray image intensity is linearly proportional to X-ray radiationintensity (dose). Meaning, double X-ray radiation intensity (dose) willdouble the X-ray image intensity. The 2D X-ray image intensity map, isused to determine which region (pixel) requires more X-ray attenuationand which region (pixel) requires less. In other words, the blackregions in the image require a higher X-ray dose, while the whiteregions in the image require a lower X-ray dose. This is achieved by thetotal magnetic field generated by the coils in the 2D pixel array. Themagnetic field strength generated by a coil is proportional to thecurrent flowing through the coil. The shape and strength of the totalmagnetic field depends on the magnetic field generated by all coils. Theshape and thickness of the material inside the 3D X-ray attenuator isformed based on the 2D X-ray image intensity map through the magneticfield generated by the coils in the 2D pixel array.

FIG. 8 illustrates a schematic diagram of an exemplary embodiment of a2D pixel array 150 of a real-time controllable 3D X-ray attenuator. Ifthe dimension of the pixel array 150 is too large to re-fresh themagnetic force fast enough, we can double the re-fleshing rate bycutting off the data lines 158, 159 in the middle of the array 150 andapply data modules 162, 163 on both sides of the data lines 158, 159 asshown.

The 2D pixel array 150 includes a plurality of pixels 152 with thin filmelectric coils 154 and switching thin film field-effect transistors 156.Each pixel 152 includes a thin film electric coil 154 connected to athin film field effect transistor 156 functioning as a switch andlocated at the intersection of a data line 158 and a scan line 160. Thedata lines 158 are coupled to a data module 162 and the scan lines 160are coupled to a scan module 164. The data module 162 and scan module164 are configured to control the pixels 152 of the pixel array and tocontrol the real-time controllable 3D X-ray attenuator.

The pixels 152 of the pixel array 150 are organized into a plurality ofrows and columns. The gates of the thin film field-effect transistors156 in each row are connected together and coupled to a scan line 160.Similarly, the sources of the thin film field-effect transistors 156 ineach column are connected together and coupled to a data line 158. Thedrains of the thin film field-effect transistors 156 are connected tothe thin film electric coils 154.

FIG. 9 illustrates a schematic diagram of an exemplary embodiment of areal-time controllable 3D X-ray attenuator 216. In order to control thedistribution and thickness of the mixture of ferromagnetic material andmedium X-ray attenuation material in the real-time controllable 3D X-rayattenuator 216, the real-time controllable 3D X-ray attenuator 216includes additional electric coils 280 positioned along the at least onesidewall 248 of the real-time controllable 3D X-ray attenuator 216. Thestronger the magnetic field along the at least one sidewall 248 of thereal-time controllable 3D X-ray attenuator 216 compared to those in thepixel array, the less mixture of ferromagnetic material and medium X-rayattenuation material will be located inside the X-ray field in themiddle of the pixel array. The required power and electrical connectionsbetween the pixel array, additional electric coils and the systemcontroller of the X-ray imaging system can be through a wireless orwired connection.

The real-time controllable 3D X-ray attenuator 216 includes a top panel242, a bottom panel 244, at least one sidewall 246 joining the top panel242 to the bottom panel 244, and an open area 248 between the top panel242, bottom panel 244, and at least one sidewall 246. The top panel 242and the bottom panel 244 are spaced apart from each other by the atleast one sidewall 246 and are parallel with each other. In an exemplaryembodiment, the top panel 242, bottom panel 244, and at least onesidewall 246 may be made of a low X-ray attenuation material such asglass, carbon fiber, aluminum, etc. The open area 248 is at leastpartially filled with a mixture of ferromagnetic material and mediumX-ray attenuation material (not shown). The mixture of ferromagneticmaterial and medium X-ray attenuation material acts as a filter thatonly allows a portion of the beam of X-ray radiation to go through the3D X-ray attenuator. A 2D pixel array 250 may be integrated into the toppanel 242 of the 3D X-ray attenuator 216. In an exemplary embodiment,the 2D pixel array 250 may be integrated into the bottom panel 244 ofthe 3D X-ray attenuator 216. In another exemplary embodiment, the 2Dpixel array 250 may be integrated into the top panel 242 and the bottompanel 244 of the 3D X-ray attenuator 216.

As noted above, embodiments within the scope of the included programproducts comprising machine-readable media for carrying or havingmachine-executable instructions or data structures stored thereon. Suchmachine-readable media can be any available media that can be accessedby a general purpose or special purpose computer or other machine with aprocessor. By way of example, such machine-readable media may compriseRAM, ROM, PROM, EPROM, EEPROM, Flash, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to carry or store desired program code inthe form of machine-executable instructions or data structures and whichcan be accessed by a general purpose or special purpose computer orother machine with a processor. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or a combination of hardwired or wireless) to amachine, the machine properly views the connection as a machine-readablemedium. Thus, any such a connection is properly termed amachine-readable medium. Combinations of the above are also includedwithin the scope of machine-readable media. Machine-executableinstructions comprise, for example, instructions and data which cause ageneral purpose computer, special purpose computer, or special purposeprocessing machines to perform a certain function or group of functions.

Embodiments are described in the general context of method steps whichmay be implemented in one embodiment by a program product includingmachine-executable instructions, such as program code, for example inthe form of program modules executed by machines in networkedenvironments. Generally, program modules include routines, programs,objects, components, data structures, etc. that perform particular tasksor implement particular abstract data types. Machine-executableinstructions, associated data structures, and program modules representexamples of program code for executing steps of the methods disclosedherein. The particular sequence of such executable instructions orassociated data structures represent examples of corresponding acts forimplementing the functions described in such steps.

Embodiments may be practiced in a networked environment using logicalconnections to one or more remote computers having processors. Logicalconnections may include a local area network (LAN) and a wide areanetwork (WAN) that are presented here by way of example and notlimitation. Such networking environments are commonplace in office-wideor enterprise-wide computer networks, intranets and the Internet and mayuse a wide variety of different communication protocols. Those skilledin the art will appreciate that such network computing environments willtypically encompass many types of computer system configurations,including personal computers, hand-held devices, multi-processorsystems, microprocessor-based or programmable consumer electronics,network PCs, minicomputers, mainframe computers, and the like. Otherexemplary embodiments may also be practiced in distributed computingenvironments where tasks are performed by local and remote processingdevices that are linked (either by hardwired links, wireless links, orby a combination of hardwired or wireless links) through acommunications network. In a distributed computing environment, programmodules may be located in both local and remote memory storage devices.

An exemplary system for implementing the method might include a generalpurpose computing device in the form of a computer, including aprocessing unit, a system memory, and a system bus that couples varioussystem components including the system memory to the processing unit.The system memory may include read only memory (ROM) and random accessmemory (RAM). The computer may also include a magnetic hard disk drivefor reading from and writing to a magnetic hard disk, a magnetic diskdrive for reading from or writing to a removable magnetic disk, and anoptical disk drive for reading from or writing to a removable opticaldisk such as a CD ROM or other optical media. The drives and theirassociated machine-readable media provide nonvolatile storage ofmachine-executable instructions, data structures, program modules andother data for the computer.

Those skilled in the art will appreciate that the embodiments disclosedherein may be applied to the formation of any medical navigation system.Certain features of the embodiments of the claimed subject matter havebeen illustrated as described herein, however, many modifications,substitutions, changes and equivalents will now occur to those skilledin the art. Additionally, while several functional blocks and relationsbetween them have been described in detail, it is contemplated by thoseof skill in the art that several of the operations may be performedwithout the use of the others, or additional functions or relationshipsbetween functions may be established and still be in accordance with theclaimed subject matter. It is, therefore, to be understood that theappended claims are intended to cover all such modifications and changesas fall within the true spirit of the embodiments of the claimed subjectmatter.

As noted above, embodiments within the scope of the included programproducts comprising machine-readable media for carrying or havingmachine-executable instructions or data structures stored thereon. Suchmachine-readable media can be any available media that can be accessedby a general purpose or special purpose computer or other machine with aprocessor. By way of example, such machine-readable media may compriseRAM, ROM, PROM, EPROM, EEPROM, Flash, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium which can be used to carry or store desired program code inthe form of machine-executable instructions or data structures and whichcan be accessed by a general purpose or special purpose computer orother machine with a processor. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or a combination of hardwired or wireless) to amachine, the machine properly views the connection as a machine-readablemedium. Thus, any such a connection is properly termed amachine-readable medium. Combinations of the above are also includedwithin the scope of machine-readable media. Machine-executableinstructions comprise, for example, instructions and data which cause ageneral purpose computer, special purpose computer, or special purposeprocessing machines to perform a certain function or group of functions.

Those skilled in the art will appreciate that the embodiments disclosedherein may be applied to the formation of any X-ray imaging system.Certain features of the embodiments of the claimed subject matter havebeen illustrated as described herein, however, many modifications,substitutions, changes and equivalents will now occur to those skilledin the art. Additionally, while several functional blocks and relationsbetween them have been described in detail, it is contemplated by thoseof skill in the art that several of the operations may be performedwithout the use of the others, or additional functions or relationshipsbetween functions may be established and still be in accordance with theclaimed subject matter. It is, therefore, to be understood that theappended claims are intended to cover all such modifications and changesas fall within the true spirit of the embodiments of the claimed subjectmatter.

What is claimed is:
 1. An X-ray imaging system comprising: an X-raysource that emits X-ray radiation; an X-ray collimator positionedadjacent to the X-ray source; a real-time controllable 3D X-rayattenuator; a digital X-ray detector; and a system controller coupled tothe X-ray source, the X-ray collimator, the real-time controllable 3DX-ray attenuator, and the digital X-ray detector for controlling thereal-time controllable 3D X-ray attenuator to reduce X-ray radiationdose and improve image quality; wherein the real-time controllable 3DX-ray attenuator includes a top panel; a bottom panel; at least onesidewall joining the top panel to the bottom panel; and an open areabetween the top panel, the bottom panel and the at least one sidewall;wherein the open area is at least partially filled with a mixture offerromagnetic material and medium X-ray attenuation material; andwherein the mixture of ferromagnetic material and medium X-rayattenuation material includes iron (Fe) and copper (Cu).
 2. The X-rayimaging system of claim 1, wherein the real-time controllable 3D X-rayattenuator filters a beam of X-ray radiation coming from the X-raycollimator into a filtered beam of X-ray radiation.
 3. The X-ray imagingsystem of claim 1, wherein the top panel, the bottom panel, and the atleast one sidewall is made of a low X-ray attenuation material.
 4. TheX-ray imaging system of claim 1, wherein the mixture of ferromagneticmaterial and medium X-ray attenuation material is a solid material. 5.The X-ray imaging system of claim 4, wherein the mixture offerromagnetic material includes iron (Fe) mixed with neodymium (Nd) andthe mixture of medium X-ray attenuation material includes copper (Cu)mixed with tungsten (W).
 6. The X-ray imaging system of claim 1, whereinthe mixture of ferromagnetic material and medium X-ray attenuationmaterial is a liquid material.
 7. The X-ray imaging system of claim 6,wherein the mixture of ferromagnetic material and medium X-rayattenuation material is iron (Fe) and/or copper (Cu) suspended in water.8. The X-ray imaging system of claim 1, wherein the real-timecontrollable 3D X-ray attenuator includes at least one 2D pixel arraywith a plurality of pixels of thin film electric coils and switchingthin film field-effect transistors.
 9. The X-ray imaging system of claim8, wherein the at least one 2D pixel array is integrated into the toppanel of the real-time controllable 3D X-ray attenuator.
 10. The X-rayimaging system of claim 8, wherein the at least one 2D pixel array isintegrated into the bottom panel of the real-time controllable 3D X-rayattenuator.
 11. The X-ray imaging system of claim 8, wherein at leastone 2D pixel array is integrated into the top panel of the real-timecontrollable 3D X-ray attenuator and at least one 2D pixel array isintegrated into the bottom panel of the real-time controllable 3D X-rayattenuator.
 12. The X-ray imaging system of claim 1, further comprisinga 2D X-ray image intensity map generated from a pre-acquisition image ina single shot radiography application or an image frame at the beginningof a fluoroscopic sequence in a fluoroscopy application.
 13. The X-rayimaging system of claim 1, wherein the real-time controllable 3D X-rayattenuator further includes a plurality of electric coils coupled to theat least one sidewall of the real-time controllable 3D X-ray attenuator.14. A real-time controllable 3D X-ray attenuator comprising: a toppanel; a bottom panel; at least one sidewall joining the top panel tothe bottom panel; an open area between the top panel, bottom panel, andat least one sidewall; and at least one 2D pixel array coupled to atleast one of the top panel and the bottom panel, the at least one 2Dpixel array having a plurality of pixels of thin film electric coils andswitching thin film field-effect transistors; wherein the open area isat least partially filled with a mixture of ferromagnetic material andmedium X-ray attenuation material; and wherein the mixture offerromagnetic material and medium X-ray attenuation material includesiron (Fe) and copper (Cu).
 15. The real-time controllable 3D X-rayattenuator of claim 14, wherein the mixture of ferromagnetic materialand medium X-ray attenuation material is a mixture of iron (Fe) andcopper (Cu) suspended in water.
 16. The real-time controllable 3D X-rayattenuator of claim 14, wherein the real-time controllable 3D X-rayattenuator is controlled with the use of a 2D X-ray image intensity mapthat is generated from an X-ray imaging system.
 17. A method ofcontrolling a 3D X-ray attenuator in real-time, the method comprisingthe steps of: acquiring a pre-acquisition image or an image frame froman X-ray imaging system; dividing the pre-acquisition image or imageframe into N×N regions through the use of an image processing system;determining the average X-ray image intensity in each N×N region tocreate a 2D X-ray image intensity map; determining the desired X-rayattenuation in each N×N region from the average X-ray image intensity ineach N×N region; and using the desired X-ray attenuation in each N×Nregion of the 2D X-ray image intensity map to control current applied toat least one coil of the 3D X-ray attenuator.